Heil Sound DT-1 Flush Mount for PL-2T Overhead Broadcast Boom DT-1 Flush Mount for PL-2T Overhead Broadcast Boom The flush-mount Heil DT-1 works with the Heil PL-2T overhead broadcast boom Drill a 1-1/2" hole in the desk top, then tighten the large washer and nut of the DT-1 under the desk The flush-mount Heil DT-1 works with the Heil PL-2T overhead broadcast boom Drill a 1-1/2" hole in the desk top, then tighten the large washer and nut of the DT-1 under the desk